The invention relates idlers, and more particularly, to flexible pneumatic idlers.
Transmission of power by belt can be accomplished by a driver pulley and a single or series of driven pulleys about which a belt is trained. For proper operation, it is necessary for the belt to maintain a certain preload as it operates between the driver and the driven. In such a case, the belt can be trained over an idler which allows the belt preload to be maintained with minimal loss of efficiency.
Idlers generally comprise a base or axle that is mounted on a non-rotating surface. The belt bearing surface or pulley is then rotatably connected to the axle by means of a bearing. The bearing may be a ball bearing type having an inner and outer race. In most arrangements, the inner race of the ball bearing is attached to the idler base or to the non-rotating mounting surface directly. The idler pulley is then attached to the outer race of the ball bearing. The outer race and the pulley rotate together. Other bearing types may comprise sleeve bearings or needle bearings.
Idlers may comprise a toothed belt surface or smooth belt surface. Generally idlers comprise a non-flexible material such as plastic or phenolic.
Toothed belt drives are also known for motorcycle motors. A belt is routed between the crankshaft and the transmission shaft. The belts are installed with a certain preload in order to avoid skipping. It is necessary to use a tensioner bearing on the belt in order to maintain the proper preload because the crankshaft and the transmission shaft are on fixed centers. Prior art idlers comprise a non-compressible material mounted on a bracket or mounting surface. The idler runs on the belt and the spring provides the necessary preload.
Representative of the art is U.S. Pat. No. 5,413,536 to Wong et al. (1995) that discloses a pulley idler that is an integral member and has two cylindrical end portions with a flexible middle portion between them.
Also representative of the art is U.S. Pat. No. 5,388,656 to Lagasse (1995) that discloses a traction unit for the road wheel of a farm tractor comprising, in part, idlers that each comprise a pneumatic tire located in the same plane as the vehicle tire.
The prior art idlers do not provide a flexible member having a gas chamber at an ambient pressure. Nor does the prior art teach an idler that operates in a deformed compressed state. Nor does the prior art teach an idler that dampens vibrations of a belt.
What is needed is a flexible idler having a gas chamber at an ambient pressure. What is needed is a flexible idler that operates in a deformed compressed state. What is needed is a flexible idler that damps vibrations of a belt. The present invention meets these needs.
The primary aspect of the invention is to provide a flexible idler having a gas chamber having an ambient pressure.
Another aspect of the invention is to provide a flexible idler that operates in a deformed compressed state.
Another aspect of the invention is to provide a flexible idler that damps vibrations of a belt.
Another aspect of the invention is to provide a flexible idler that is highly compressible.
Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.
The invention comprises an idler having a flexible member. The flexible member comprises a rubber or elastomeric material. The flexible member also defines a gas chamber. The spring rate of the flexible member is a function of the flexible material and the size of and pressure in the chamber. A belt bearing surface of the flexible member bears upon a belt trained between two pulleys. The flexible member is highly compressible in response to a preload force created as the pulley presses against the belt. The flexible member damps vibrations in the belt during operation. This results in quieter operation of the idler/pulley system. The inventive idler is particularly well adapted to operating in small confined areas with belts under high loads and speeds.